Autism and Developmental Delays
Are missed milestones the traits of a spectrum disorder?
Alita Ong / Stocksy United
Medically reviewed by Stephanie Hartselle, MD
Children diagnosed with autism spectrum disorder (ASD) often have developmental delays, defined as reaching their social, emotional, communication, cognitive, and physical milestones in different ways than neurotypical people do.
But "developmental delays" is an oversimplification that fails to capture the breadth of development in autistic people. Most autistic children reach some of their developmental milestones on time or early—sometimes extraordinarily so. Others may be late, lose ground over time, or not develop at all.
This article seeks to present a comprehensive and accurate view of developmental milestones and what they can mean in the lives of autistic children. It explains some of the traits to watch for, but also why the idea of "delays" in people who simply learn and live differently can be misleading.
What Are the Developmental Milestones?
The Centers for Disease Control and Prevention (CDC) divides developmental milestones into groups: movement/physical, cognitive, language/communication, social/emotional. They list specific levels of achievement for each age, starting with 1 month and moving through adolescence.
While they make it clear that children may not reach any given milestone at the precise age outlined, they also suggest that parents keep an eye out to be sure their child is at or close to what's expected.
Most autistic children are diagnosed at a relatively young age—often by the age of 3. Here is a simplified list of milestones for 3-year-olds from the CDC:
Social and Emotional
Calms down within 10 minutes after you leave
Notices other children and joins them to play
Language/Communication
Says their first name when asked
Can have a conversation with at least two back-and-forth exchanges
Talks well enough for strangers to understand most of the time
Can ask “who,” “what,” “where,” or “why” questions
Names an action that is happening in a book or picture, such as "running" or "eating"
Cognitive (Learning, Thinking, Problem Solving)
Copies a circle with pencil or crayon
Avoids touching hot objects like a stove, when warned
Movement/Physical Development
Can feed themselves using a fork
Can string items like large beads or macaroni
Can put on certain clothes by themselves, such as a jacket or pants
Why Children Miss Developmental Milestones
There are many reasons why children miss developmental milestones. In most cases, there's no particular cause for concern.
That's because:
Children are different from one another, and naturally develop at different rates.
Children who are born prematurely may miss milestones but usually catch up.
Children assigned male at birth (boys) are often slower to develop than those assigned female (girls), but almost always catch up.
Many children are so focused on certain milestones that they may miss others. For example, a very physically adept child may reach advanced physical milestones and then later catch up on social milestones.
Early medical challenges may slow development, but most children are able to catch up to their same-age peers.
Certain correctable challenges, such as difficulty with hearing, can slow early development but have little impact on long-term development once addressed.
With that said, there are times when developmental delays may indicate a concern such as autism.
When Developmental Delays May Suggest Autism
The CDC provides a list of issues that are considered early traits of autism, though they may also occur in those without a spectrum disorder.
Autism is more likely when children have more than one of these issues or have other related issues in the social/emotional or communication realms:
Can’t work simple toys (such as pegboards, simple puzzles, turning handles)
Doesn't respond to name by 9 months of age
Doesn't show facial expression (like being sad, angry, or happy) by 9 months of age
Uses few or no gestures (such as waving goodbye) by 12 months of age
Doesn’t play pretend or make-believe by 48 months of age
Doesn't play simple interactive games such as pat-a-cake by 12 months of age
Doesn't notice other children and join them in play by 36 months of age
Doesn't notice when others are upset or hurt by 24 months of age
Does not share interests with others by 15 months of age
Shows very specific, repetitive behaviors or interests
Does not sing, dance, or act for you by 60 months of age
Loses skills they once had
Why Monitoring for Autism This Way Can Be Misleading
Sometimes, autistic children miss multiple milestones and have clear and obvious developmental delays. Often, however, missed milestones can be masked or even invisible.
This is because autistic children aren't simply delayed; they learn and behave differently from their typical peers.
In addition, autism is rarely obvious from birth. Many autistic children develop like their neurotypical counterparts for a period of time and then either slow down, develop in small ways, or actually regress.
Because of this, it can be tough to spot autism just by watching for missed developmental milestones.
Related: How Autism in Children Is Diagnosed
Masked or Hidden Delays in Autism
Some autistic children have severe cognitive delays, behavioral challenges, or physical "stims" (rocking or flapping) that make clear they are developing differently. But many don't. When that's the case, developmental delays may be hard to spot.
There are a few groups of children whose developmental delays may not be obvious until social, emotional, or communication demands increase (usually after grades 1 or 2).
Girls
Autism generally causes children to be quiet, socially withdrawn, and less likely to raise their hands or speak out. They may appear "dreamy" or inattentive.
These behaviors are social expectations of girls in many parts of the world. Thus, young autistic girls who are not meeting developmental milestones may slide under the radar. They are often labeled as "shy and quiet," and, perhaps, not terribly bright.
It may take quite a while for parents and teachers to notice other autism traits in girls.
Takeaway
Children, and especially autistic girls with lower support needs, are sometimes able to hide or overcome developmental delays, which can make milestones an unreliable measure to use for diagnosis.
Learn More: Autism Traits in Girls
Black Children
Autism is often overlooked in Black children (especially Black girls) who are often diagnosed later than their White counterparts. That's despite the fact that some studies now find a higher incidence of autism spectrum disorder (ASD) in Black children than in White children, including one that looks at diagnosis by a relatively late age of 8 years.
Delays in diagnosis and treatment may play a role in the higher rates of co-occurring intellectual disability seen in Black children. Autistic black children also tend to be misdiagnosed more often, with conditions including behavioral problems or attention deficit disorder. It's important for caregivers to advocate for access to care and appropriate therapies and resources.
Children With Impressive Intelligence or Splinter Skills
Quite a few autistic children are very bright or have surprising skills that are far beyond their years.
For example, some autistic children can solve complex puzzles, read at a very young age, or show impressive math, music, or computer skills. They may also have advanced vocabularies in their areas of special interest.
When this is the case, parents and teachers may not notice that the same child who can solve complex math equations is unable to play imaginatively or catch a ball. They also may not be able to identify the difference between a grasp of facts, and meaningful understanding and knowledge.
Takeaway
Sometimes, autistic children can appear to gain important skills but they are unable to use them in real-world situations. Many have so-called "splinter" skills, which can be very advanced but not useful in daily life. Up to 10% of autistic people may have splinter skills.
Learn More: Splinter Skills in Autism
Children With Empathetic Siblings or Peers
In some families and classrooms, empathetic siblings or peers can actually mask another child's autism.
These children take it upon themselves to learn to understand their autistic peer and speak for them. While this is undoubtedly kind and caring, it's also a form of enabling that can make it hard to know what the autistic child really can do for themself.
Children of Parents With Autistic Traits
It's not unusual for autistic children to have parents who could be diagnosable as autistic with lower support needs, or who have so-called "shadow" traits of autism.
When this is the case, parents may see their children as developing typically (just like they did). Some parents may not want their child to be labeled as autistic because they struggle with the idea that the same could be said about them.
If Your Child Has Developmental Delays
If you think your child has developmental delays and may be autistic, take action. Ask your child's healthcare provider to screen for delays, with a special emphasis on social, communication, and emotional skills.
If your intuition was incorrect, you can put a potential diagnosis out of mind. If your child does, indeed, have developmental delays, you've taken prompt action to get to the bottom of why they are occurring and what can be done to help them overcome any challenges.
Related: A Checklist of Autism Traits
